Stocks are young trees or shrubs raised from seed, suckers, layers, and cuttings, for the reception of buds or grafts from other trees or shrubs of a kindred species.

Although the sap increases in specific gravity, and, consequently, obtains most accession of solid matter during its progress up the stem, yet the matter thus obtained is not of paramount importance, nor absolutely controlling the subsequent changes to be effected; for, in such case, the green-gage would be altered by its plum stock, and the nonpareil by its crab stem. So far from this being the case, the old gardener's maxim, ' the graft overruleth the stock quite,' is consonant with truth, though it is to be taken with some reservation. The graft prevails, and retains its qualities, yet the stock has the power of influencing its productiveness, as well as the quality of the fruit. Thus, a tree having an expansive foliage, and robust growth, indicative of large sap vessels, and vigorous circulation, should never be grafted upon a stock oppositely characterized, for the supply of sap will not be sufficient. Illustrations are afforded by the codlin never succeeding so well on a crab, nor a bigoureau on a wild cherry, as they do on freer growing stocks. Indeed I have no doubt that every tree and shrub succeeds best, is most productive, and freest from disease, if it be supplied with sap from roots, and through a stem, of its own particular kind.

This is evident to common sense; nor would any fruit scion be grafted upon a stock of another species or variety, if it were not that such stocks are most easily obtainable. For example, our choicest cherries are, for the reason assigned, grafted or budded upon the wild cherry; and every one must have noticed the frequently-occurring consequence, an enlargement, appearing like a wen, encircling the tree just above where the graft and the stock joined, the growth of the former having far outstripped that of the latter. If a tree could be nourished from its own roots, from organs assigned by its Creator, as those best suited to supply the most appropriate quantity and quality of sap, there can be no doubt that it would be productive of benefit; and this desideratum seems to be secured by the plan suggested by M. Aibrett in the instances of apples and pears; and I see no reason forbidding its adoption to any other grafted tree. He recommends the grafts always to be inserted close to the surface of the ground, or they might be even rather below the surface, by scooping out the earth around the stems of the stocks.

When planted out, the lowest extremity of the graft should be about four inches below the surface.

After two or three years, at the close of June, the soil should be removed, and just above the junction of the graft and stock, with a gouge, one fourth of the bark removed by four cuts on opposite sides of the stem.

"The cuts being deep enough to remove the inner bark, and the wounds covered immediately with rich soil, formed of one part putrescent cow-dung, and two parts maiden loam, if kept constantly moist with water, and occasionally with liquid manure, roots will usually be speedily emitted, especially if the place where a bud once was formed be thus kept moist beneath the soil.

But the stock has some other influence over the sap, besides limiting the quantity supplied to the scion, an influence not only arising from the size of its vessels, but upon its susceptibility to heat. It has a further influence over the scion, by the sap becoming more rich, indicated by its acquiring a great-r: specific gravity in some stocks than in others, during its upward progress. The specific gravity of the sap of a black cluster vine stock, on which a black Hamburgh had been grafted, was, when obtained six inches from the ground, 1003; and at five feet from the ground, 1006; but the same black Hamburgh, growing upon its own roots, had specific gravities at corresponding heights of 1004 and 1009.

This increase is of great importance to a tree's growth, when the quantity of sap passing annually through its vessels is considered. The exact amount of this it is, perhaps, impossible to discover; but its extent may be appreciated by the quantity of moisture their roots are known to imbibe, and by the facts that a small vine branch has poured out sixteen ounces of sap in twenty-four hours; a birch tree, a quantity equal to its own weight, during the bleeding season; and a moderate sized maple, about two hundred pints, during the same period.

The habit of the stock, also, is of much more importance than is usually considered. If it grows more rapidly, or has larger sap vessels than the scion or bud, an enlargement occurs below these; but if they grow more rapidly than the stock, an enlargement takes place just above the point of union. In either case, the tree is usually rendered temporarily more prolific; but in the case where the stock grows more slowly, the productiveness is often of very short duration, the supply of sap annually becoming less and less sufficient to sustain the enlarged production of blossom and leaves. This very frequently occurs in the freer growing cherries, when inserted upon the wild species; and still more frequently to the peach and apricot upon stocks of the slow growing plums. It is highly important, therefore, to employ stocks, the growth of which is as nearly similar as may be to the parent of the buds or scion.

The earlier vegetation of the stock than of the bud or graft is also important ; for, if these are earliest in development, they are apt to be exhausted and die before the flow of sap has enabled granulation and union between the faces of the wounds, at the junction, to occur. Mr, Knight's observations upon this point are the results of experience, and are so consonant with the suggestions of science, that I will quote them in his own words, without comment: -

"The practice of grafting the pear on the quince stock, and the peach and apricot on the plum, when extensive growth and durability are wanted, is wrong; but it is eligible whenever it is wished to diminish the vigour and growth of the tree, and where its durability is not thought important. The last remark applies chiefly to the Moor-park apricot, the abricot peche, or abri-cot de Nancy, of the French.